Before Yellow Submarine, animation was a mild, goody-goody world of personality-free gloved mice and cartoon bears stealing picnic baskets. Only the Fleischer brothers in the 1930s dared to do really weird stuff with their early Popeye cartoons, and most of that is unknown to the general public. But after Yellow Submarine, it was a wholly different world. It wasn't just for kids. It was satire and art and, most of all, subversion.